The paper presents the formulation of a specific computational model for the seismic response of ... more The paper presents the formulation of a specific computational model for the seismic response of masonry structures. In this field, there is the need of models that are simplified enough to allow parametric dynamical analyses, but should also account for the peculiar behaviour of the masonry material subjected to cyclic loadings that cause heavy mechanical degradation. Rigid elements are adopted, and in particular the elements are plane quadrilaterals connected to each other by two normal springs and one shear spring at each side. The mechanical characteristics of these connections are defined with attention to the orthotropy and the micro-structure effects that can be important when the mortar joints suffer high mechanical degradation. A simplified phenomenological description is proposed for the cyclic behaviour of the masonry material out-of the linear elastic field, with different hysteretic laws for the axial and shear connections between rigid elements.
The macroscopic modelling of in-plane elastic behaviour of composite solids made with regular ort... more The macroscopic modelling of in-plane elastic behaviour of composite solids made with regular orthotropic texture is the object of the present study. In this field, a specific approach has been recently proposed by the author, based “rigid elements” whose mechanical characteristics are directly identified from the composite response without homogenization [1]. The theoretical relation between an orthotropic Cosserat continuum and the proposed rigid elements is explicitly given here. Then, referring to masonry-like textures, the elastic moduli of the corresponding Cosserat continuum are evaluated, and the passage to the rigid element model is performed. Depending on various factors, numerical results evidentiate the impact of the composite texture on the strain field map at the micro and macro-scale, with different shear responses of the vertical and horizontal joints and the local rotation of the blocks. Finally, the capability of the proposed rigid elements to discern at the macro-...
A numerical investigation on the load carrying capacity of a glass beam modelled as a material wi... more A numerical investigation on the load carrying capacity of a glass beam modelled as a material with a random strength distribution is presented. The strength values were distributed randomly within the beam by a Monte Carlo simulation, according to statistical distributions calibrated on experimental results obtained from literature. The elastic-plastic problem has been solved using two different computational discrete approaches implemented in two inhouse computer codes: a Rigid Body-Spring Model (RBSM) and a mesh-free numerical method arising from lattice-based Peridynamics. Being discrete approaches directly based on algebraic governing equations, they are suitable in problems involving brittle failure, because cracks are not viewed as a pathology of the displacement field. By providing an appropraiate mathematical and computational framework, the differences and analogies of these models are discussed and then the variability of the load capacity of the structural element is evaluated as a function of the statistics of the strength related to the size of the defects. The results obtained show that both RBSM and Peridynamics seem to be powerful tools for modelling the failure of brittle materials with heterogeneous strength properties
An original full orthotropic model for in-plane linear elasticity is proposed in the micropolar p... more An original full orthotropic model for in-plane linear elasticity is proposed in the micropolar peridynamic analysis framework. The analytical formulation is derived from the definition of a specific microe-lastic energy function for micropolar nonlocal lattices which allows to obtain, for the first time, an orthotropic bond-based model characterized by four independent elastic moduli. An important feature of the model is that the bond properties, i.e. the elastic constants, are continuous functions of the bond orientation in the principal material axes. The introduction of the bond shear stiffness and the definition of a bond shear deformation measure which accounts for particle\u2019s rotation, on one hand eliminates the restriction of two independent constants that affects other bond-based orthotropic peridynamic formulations, and on the other makes the model suitable in predicting the mechanical behavior of a wide variety of Cauchy orthotropic materials undergoing homogeneous and non-homogeneous deformations. The accuracy of the proposed model in linear elasticity has been verified through simulating uniaxial extension test of a composite lamina with a central circular hole and natural frequency analyses considering different orientations of the principal material reference system
Rigid elementsareproposedfor aspecificdiscretemodelthatisdevelopedwith the aim to investigatetheg... more Rigid elementsareproposedfor aspecificdiscretemodelthatisdevelopedwith the aim to investigatetheglobaldynamicalresponseof masonrybuildingssubjected to strong earthquakes that cause mechanical degradation. In particular, the elements are plane quadrilaterals connected to each other by two normal springs and one shear spring at each side. The mechanical characteristics of these connections are defined paying attention to the micro-structure effects that arise when the mortar joints suffer high mechanical degradation. In particular, the micro-structure effect of inter-locking and local rotation of the blocks can be approximated by properly assigning the constitutive laws of the connection springs. A main computational advantage of the present approach consists in allowing a simplified description of the hysteretic response by defining separate phenomenological behaviours for the axial and the shear elastic connections that are based on experimental tests available in the technical lite...
The paper presents the computational modelling and the seismic damage assessment of a typology of... more The paper presents the computational modelling and the seismic damage assessment of a typology of façade that is recurring among the churches built during the colonial period in México, between 16 and 18 century. This typology is symmetric, with two relatively stubby bell towers on either side of the main façade itself, while the openings are usually aligned along the vertical axis of symmetry, including a portal that is much wider than the window underneath the tympanum. Even if these churches were built differently, according to the regional seismicity, this notwithstanding we considered This is an “archetype model” whose characteristics can be considered as a good basis to be representative of this typology in general, even if there is some local variability, mainly related to the regional level of seismicity. The main seismic collapse mechanisms of this typology tend to involve both the towers and the central part of the façade with damages that can be related both to in-plane s...
The paper presents the formulation of a specific computational model for the seismic response of ... more The paper presents the formulation of a specific computational model for the seismic response of masonry structures. In this field, there is the need of models that are simplified enough to allow parametric dynamical analyses, but should also account for the peculiar behaviour of the masonry material subjected to cyclic loadings that cause heavy mechanical degradation. Rigid elements are adopted, and in particular the elements are plane quadrilaterals connected to each other by two normal springs and one shear spring at each side. The mechanical characteristics of these connections are defined with attention to the orthotropy and the micro-structure effects that can be important when the mortar joints suffer high mechanical degradation. A simplified phenomenological description is proposed for the cyclic behaviour of the masonry material out-of the linear elastic field, with different hysteretic laws for the axial and shear connections between rigid elements.
The macroscopic modelling of in-plane elastic behaviour of composite solids made with regular ort... more The macroscopic modelling of in-plane elastic behaviour of composite solids made with regular orthotropic texture is the object of the present study. In this field, a specific approach has been recently proposed by the author, based “rigid elements” whose mechanical characteristics are directly identified from the composite response without homogenization [1]. The theoretical relation between an orthotropic Cosserat continuum and the proposed rigid elements is explicitly given here. Then, referring to masonry-like textures, the elastic moduli of the corresponding Cosserat continuum are evaluated, and the passage to the rigid element model is performed. Depending on various factors, numerical results evidentiate the impact of the composite texture on the strain field map at the micro and macro-scale, with different shear responses of the vertical and horizontal joints and the local rotation of the blocks. Finally, the capability of the proposed rigid elements to discern at the macro-...
A numerical investigation on the load carrying capacity of a glass beam modelled as a material wi... more A numerical investigation on the load carrying capacity of a glass beam modelled as a material with a random strength distribution is presented. The strength values were distributed randomly within the beam by a Monte Carlo simulation, according to statistical distributions calibrated on experimental results obtained from literature. The elastic-plastic problem has been solved using two different computational discrete approaches implemented in two inhouse computer codes: a Rigid Body-Spring Model (RBSM) and a mesh-free numerical method arising from lattice-based Peridynamics. Being discrete approaches directly based on algebraic governing equations, they are suitable in problems involving brittle failure, because cracks are not viewed as a pathology of the displacement field. By providing an appropraiate mathematical and computational framework, the differences and analogies of these models are discussed and then the variability of the load capacity of the structural element is evaluated as a function of the statistics of the strength related to the size of the defects. The results obtained show that both RBSM and Peridynamics seem to be powerful tools for modelling the failure of brittle materials with heterogeneous strength properties
An original full orthotropic model for in-plane linear elasticity is proposed in the micropolar p... more An original full orthotropic model for in-plane linear elasticity is proposed in the micropolar peridynamic analysis framework. The analytical formulation is derived from the definition of a specific microe-lastic energy function for micropolar nonlocal lattices which allows to obtain, for the first time, an orthotropic bond-based model characterized by four independent elastic moduli. An important feature of the model is that the bond properties, i.e. the elastic constants, are continuous functions of the bond orientation in the principal material axes. The introduction of the bond shear stiffness and the definition of a bond shear deformation measure which accounts for particle\u2019s rotation, on one hand eliminates the restriction of two independent constants that affects other bond-based orthotropic peridynamic formulations, and on the other makes the model suitable in predicting the mechanical behavior of a wide variety of Cauchy orthotropic materials undergoing homogeneous and non-homogeneous deformations. The accuracy of the proposed model in linear elasticity has been verified through simulating uniaxial extension test of a composite lamina with a central circular hole and natural frequency analyses considering different orientations of the principal material reference system
Rigid elementsareproposedfor aspecificdiscretemodelthatisdevelopedwith the aim to investigatetheg... more Rigid elementsareproposedfor aspecificdiscretemodelthatisdevelopedwith the aim to investigatetheglobaldynamicalresponseof masonrybuildingssubjected to strong earthquakes that cause mechanical degradation. In particular, the elements are plane quadrilaterals connected to each other by two normal springs and one shear spring at each side. The mechanical characteristics of these connections are defined paying attention to the micro-structure effects that arise when the mortar joints suffer high mechanical degradation. In particular, the micro-structure effect of inter-locking and local rotation of the blocks can be approximated by properly assigning the constitutive laws of the connection springs. A main computational advantage of the present approach consists in allowing a simplified description of the hysteretic response by defining separate phenomenological behaviours for the axial and the shear elastic connections that are based on experimental tests available in the technical lite...
The paper presents the computational modelling and the seismic damage assessment of a typology of... more The paper presents the computational modelling and the seismic damage assessment of a typology of façade that is recurring among the churches built during the colonial period in México, between 16 and 18 century. This typology is symmetric, with two relatively stubby bell towers on either side of the main façade itself, while the openings are usually aligned along the vertical axis of symmetry, including a portal that is much wider than the window underneath the tympanum. Even if these churches were built differently, according to the regional seismicity, this notwithstanding we considered This is an “archetype model” whose characteristics can be considered as a good basis to be representative of this typology in general, even if there is some local variability, mainly related to the regional level of seismicity. The main seismic collapse mechanisms of this typology tend to involve both the towers and the central part of the façade with damages that can be related both to in-plane s...
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Papers by S. Casolo